One of Northern Ireland\'s two main gas suppliers is to raise its prices in Greater Belfast by more than a third.Firmus Energy has ended its summer price freeze and will increase tariffs by over 35% from 1 October.It has around 8,500 customers in the greater Belfast area while Phoenix Gas has more than 130,000.Firmus said it would honour any discount agreements made to its customers.\"In May earlier this year when Phoenix increased their prices by 39%, Firmus Energy made a promise to freeze prices until the end of September this year,\" Michael Scott of Firmus said.\"We have honoured that commitment and the good news is that we plan to increase our level of discount from a planned level of 7.5% to 10%.\"UUP assembly member Mike Nesbitt said the gas price rise was \"devastatingly bad news for consumers, domestic and commercial\".The price increase in May applied to Phoenix Supply domestic and small business customers in the greater Belfast and Larne areas.At that time, the Consumer Council said the price hike was a \"massive blow\" and risked pushing more consumers into fuel poverty.In September, Firmus Energy said it would increase its prices in towns outside Belfast by 28.4% from 1 October.Firmus is the sole provider of natural gas to households in 10 towns across Northern Ireland. From / BBC